myo-Inositol, which is an essential ingredient in most higher animals, is widely used as a health functional material in the food, feed, cosmetic, and pharmaceutical fields. For example, myo-inositol is known to have an important role in the metabolism of cholesterol and fat, and is reported to be effective in preventing or treating hypercholesterolemia, etc. Additionally, myo-inositol has been used as a cosmetic material because it has skin functions such as moisture maintenance, sebum control, anti-aging via regulation of an antioxidant activity, etc.
Derivatives which can be synthesized using myo-inositol as a raw material have also been attracting attention as high value-added functional materials. For example, they have been reported as important mediators as major constituents of phosphoglycans for delivering insulin signals. In addition, as examples thereof, there are D-chiro-inositol and D-pinitol, which are known to be effective in treating type 2 diabetes, and scyllo-inositol, which is expected to be used as a therapeutic agent for Alzheimer's disease (2000. J Biol Chem. 275:18495-18502), a synthetic raw material of physiologically active substances (U.S. Pat. No. 5,412,080), and a synthetic raw material of liquid crystal compounds (German Patent No. 3,405,663).
Various methods for developing and improving the production process of myo-inositol on an industrial scale have been reported.
myo-Inositol is purified from rice bran, corn steep liquor, and the like by using conventional physiochemical extraction (acid, base, heat, pressure, etc.) methods known in the art. It is known that the production methods performed by direct extractions from the raw materials not only have a low yield but also possess a very low production efficiency due to difficulty in regulating yield and purity in the purification process because large amounts of various impurities are contained in the extract for each of the raw materials.
As another method, fermentative production methods have been reported for isolating and purifying myo-inositol from a fermentation broth by newly discovering strains possessing a high producibility of myo-inositol or by genetically modifying a synthetic metabolic pathway. The production strains include Saccharomyces cerevisiae, Candida (JP Kokai 8-00258, JP Kokai 8-38188, JP Kokai 8-89262, JP Kokai 9-117295, JP Kokai 10-42860, JP Kokai 10-42882, JP Kokai 10-42883, JP Kokai 2000-41689, JP Kokai 9-220093, JP Kokai 10-271995), Pichia pastoris (JP Kokai 2011-55722), and Escherichia coli (1999. J. Am. Chem. Soc. 121:3799-3800, International Patent No. WO2009/145838), etc. However, such fermentative methods have low productivity, and thus have not been practically applied to industrial-scale production methods.